Vegetarian cookbook recommendations?

After a recent trip to the doctors I've been told I have high blood pressure and high-ish cholesterol... I'm only 25 and generally live a healthy lifestyle so it kinda caught me off-guard. (Genetics I suppose) But in an effort to be healthier and save the environment (just finished reading "Food Matters") I'm hoping to eat more vegetarian meals. But truthfully I don't even know where to start. I've got the salads and some soups going on but there must be more beyond that.

I'm looking for recommendations on good beginner vegetarian cookbook. Recipes that are easy and healthy and can help me explore different tastes and ideas... also I'm working with a grad student budget so inexpensive would be helpful too.